On Wed, Dec 29, 2010 at 12:47:22PM -0500, Olin Lathrop wrote:
> Byron Jeff wrote:
> > I kind of like C's ability to use assignment as an expression.
>=20
> Hmm.  I rather doubt there is any real efficiency gained from that by
> reasonably written compilers.

>=20
> > Again it
> > does facilitate a compactness of expression that other languages do
> > not have the ability to accomplish.
>=20
> That may have been K&R's intent, and perhaps there was some limited reaso=
n
> for it back then, but there is certainly little reason for it now.  Clari=
ty
> is far more important than compactness, and I think should have been back
> then too.  I mostly care about compactness only as it enhances clarity.  =
Go
> too far and it detracts from clarity.

C certainly has the ability to bash clarity down into the ground if a
programmer so decides to want to do it. But there are times when clarity
and compactness do not have to be at odds. Even something as simple as:

a =3D b =3D c =3D d =3D 0;

is perfectly readable yet compact. But it's only doable if assignment is an
expression, and not a statement.

>=20
> > BTW you didn't even get to the one that just sticks in my craw:
> >
> > The default drop through action of cases in the switch statement.
>=20
> Yeah, that's another good one.  I totally agree the default should be to =
end
> the switch, not fall thru to the next case.  The C SWITCH is just a compu=
ted
> GOTO, not a real selection of multiple cases as the syntax would lead a
> casual observer to believe.  If they had named it MULTIJUMP or something,=
 it
> wouldn't bother me so much, but then I'd still want a real multi-case
> statement.
>=20
> By the way, the Pascal CASE statement does work as you describe.  For
> example:
>=20
>   choice :=3D 1;
>   case choice of
> 1:  writeln ('1 was picked');
> 3:  writeln ('2 was picked');
> 3:  writeln ('3 was picked');
> otherwise
>     writeln ('Other was picked');
>     end;
>=20
> would only result in "1 was picked" to be written.  You don't have to be =
a
> Pascal whiz to have a pretty good idea what the above code does.

I know. I learned the case statement first. That's one reason why the C
switch always drove me nuts.

>=20
> > The only argument that holds water is that since ranges are not
> > allowed,
> > the default fall through allows multiple cases to share the same code:
> >
> > choice =3D 1;
> > switch (choice) {
> >    case 1:
> >    case 2:
> >    case 3: printf("1,2, or 3 was picked\n");
> >            break;
> >    default: printf("other was picked\n");
> >            break; // Unneccessary but often put in for consistency.
> > }
>=20
> Pascal gets around it this way:
>=20
>   case choice of
> 1, 2, 3: writeln ('1, 2, or 3 was picked');
> otherwise
>     writeln ('Other was picked');
>     end;
>=20
> In other words, you can't put a bunch of cases in a row and fall thru, bu=
t
> you can give each case multiple target values.  I think that addresses yo=
ur
> concern adequately enough.

Agreed. But as you pointed out, C's switch is a computed goto and has no
facility to do that.

>=20
> > switch (choice) {
> >    case 1: continue;
> >    case 2: continue;
> >    case 3: printf("1,2, or 3 was picked\n");
> >            break;
> >    default: printf("other was picked\n");
> >            break; // Unneccessary but often put in for consistency.
> > }
>=20
> Something like that, although as Martin pointed out, CONTINUE already has
> another meaning.  I would be fine with this if a different and new keywor=
d
> were used, like NEXTCASE for example.

It's probably my C bias leaking through. Since break was multipurposed in
loops and switches, it seems natural to me that continue could have done
the same.

>=20
> > Byron A. Jeff
> > Department Chair: IT/CS/CNET
> > College of Information and Mathematical Sciences
> > Clayton State University
>=20
> Hey, when did that happen?  Congratulations!  Is that the same place you
> were before, or did you have to go elsewhere to get promoted?

Thanks.

Same place. Tenure, promotion, and put into administration all at the same
time.

>  Last I
> remember (probably a long time ago since my brain usually tunes out email
> signatures) you were someplace in Georgia.

This happened about 6 months ago. I've been out of the loop busy learning
the new job. Also we had a slight E-mail change and my old registered
E-mail wasn't available for list postings. I finally got around to
reregistering. So I plan to drop in an out with postings though I lurk
regularly.

BAJ
--=20
Byron A. Jeff
Department Chair: IT/CS/CNET
College of Information and Mathematical Sciences
Clayton State University
http://cims.clayton.edu/bjeff
--=20
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